Exactly.To clear up even more confusion.
You can run just about any gearing combination you desire, so long as the chain and sprockets are of the same type. I.E. 520 chain with 520 sprockets. %30 chain with 530 sprockets.
The " standard " thing to do when changing from a 530 - 520 chain is to go the -1 +2 format. This is just the popular thing to do, not the rule, or must have deal. You can run -2 +1, -0 +4, or even -1 -1 if you desire. It's up to you which gearing you choose.